The present invention relates generally to storing information on disks, and more particularly to a method for writing information to an array of independent disks.
Magnetic disks are typically used as secondary storage for computers. Increasing storage needs have prompted improvements in disk capacity, but at a greater user cost.
A less expensive alternative to high storage capacity disks is a disk array, consisting of a set of independent disks linked together as a single data store. The greater number of disks in the array, however, increases the possibility of disk failure. Redundant information storage is therefore necessary to increase the reliability of the array.
In one scheme, a check disk is added to the array to store the parity of the information on the disks. In another scheme, each disk in the array stores some parity information. These schemes are discussed in detail in Patterson et al., "A case for redundant arrays of inexpensive disks (RAID)", Proc. ACM SIGMOD Conf., Chicago, Ill., June 1988, 109.